Cylinder Power Balance Test

A Cylinder power balance test tests the power of each cylinder, measuring its power contribution. An engine analyzer or bidirectional scan tool disables each cylinder and records the drop in RPM as each cylinder is disabled.

Cylinder Power Balance Testing

If an analyzer is not available, disconnect the injector's connector to disable the desired cylinder. Then, use a pen and pencil to record each cylinder's drop in RPM. Removing the coil's connector or spark plug boot and disabling a cylinder's ignition too long dumps raw fuel into the exhaust, overheating the catalytic converter.

Cylinder Power Balance Test

Notice the RPM drop as the cylinder is disabled. If a cylinder's drop is not consistent with the others, this indicates a problem with that cylinder. The reasons for a cylinder not contributing include an ignition problem, fuel delivery, or a mechanical problem such as a faulty valve or worn piston rings.

Unplugged ignition coil.

Check with the manufacturer's specifications before removing the spark plug boot and remember safety first. Use a grabber or a tool that will protect your hand from the shock that may result from removing the plug cover. Some coil packs produce more than 35K volts.